Identification of a new transmembrane adaptor protein that constitutively binds Grb2 in B cells.

Journal Article (Journal Article)

Transmembrane adaptor proteins couple antigen receptor engagement to downstream signaling cascades in lymphocytes. One example of these proteins is the linker for activation of T cells (LAT), which plays an indispensable role in T cell activation and development. Here, we report identification of a new transmembrane adaptor molecule, namely growth factor receptor-bound protein 2 (Grb2)-binding adaptor protein, transmembrane (GAPT), which is expressed in B cells and myeloid cells. Similar to LAT, GAPT has an extracellular domain, a transmembrane domain, and a cytoplasmic tail with multiple Grb2-binding motifs. In contrast to other transmembrane adaptor proteins, GAPT is not phosphorylated upon BCR ligation but associates with Grb2 constitutively through its proline-rich region. Targeted disruption of the gapt gene in mice affects neither B cell development nor a nitrophenylacetyl-specific antibody response. However, in the absence of GAPT, B cell proliferation after BCR cross-linking is enhanced. In aged GAPT(-/-) mice, the number of marginal zone (MZ) B cells is increased, and other B cell subsets are normal. The serum concentrations of IgM, IgG2b, and IgG3 are also elevated in these mice. These data indicate that GAPT might play an important role in control of B cell activation and proper maintenance of MZ B cells.

Full Text

Duke Authors

Cited Authors

  • Liu, Y; Zhang, W

Published Date

  • September 2008

Published In

Volume / Issue

  • 84 / 3

Start / End Page

  • 842 - 851

PubMed ID

  • 18559951

Pubmed Central ID

  • PMC2516900

International Standard Serial Number (ISSN)

  • 0741-5400

Digital Object Identifier (DOI)

  • 10.1189/jlb.0208087


  • eng

Conference Location

  • United States